Effect of dialysate composition on the lipid response to L-carnitine supplementation.
Cumulative carnitine losses through dialysis membranes may worsen hyperlipidemia during long-term hemodialysis. However, carnitine supplementation has not shown a consistent beneficial response in hyperlipidemia. We have compared in a double-blind, cross-over study the effect of dialysate buffer composition (acetate or bicarbonate) on the serum lipid response to L-carnitine supplementation during hemodialysis. We studied nine patients (mean age, 19 years; range, 14 to 23) with hyperlipidemia undergoing maintenance hemodialysis. Plasma levels of carnitines and lipids, including total and HDL cholesterol (HDL-C) and triglycerides (TG), were measured at baseline and monthly intervals after receiving 2 grams of L-carnitine or placebo added to dialysis bath for three months. One month of carnitine supplementation in acetate hemodialysis significantly reduced plasma TG (230 +/- 95 to 136 +/- 20 mg/dl; P less than 0.05) and elevated HDL-C (50 +/- 12 to 71 +/- 26 mg/dl; P less than 0.05). However, this effect was no longer observed at the end of three months of supplementation. Bicarbonate hemodialysis had lower baseline TG values, but carnitine supplementation did not modify plasma lipids (TG:144 +/- 87 to 158 +/- 115 mg/dl; HDL-C:50 +/- 23 to 50 +/- 19 mg/dl). Both groups had a significant increase in plasma carnitine levels after carnitine supplementation. These results suggest that bicarbonate hemodialysis may add a protective effect in hyperlipidemia by reducing requirements of carnitine supplementation. On the other hand, carnitine supplementation should be considered in patients with hyperlipidemia undergoing acetate hemodialysis. The observed difference in response between acetate and bicarbonate hemodialysis may be due to enhanced formation of acetyl-CoA and fatty acid synthesis during acetate hemodialysis.